Dead connections aren't removed from pool in java memcached client?

Greg Whalin gwhalin at
Mon Aug 6 17:50:11 UTC 2007

This *should* be better in latest version of the client.  Had a bug that
fixed an internal conn leak.  Try it and let me know.


On 8/6/07, Eli Bingham <eli at> wrote:
> Hey memcached folks,
> We've encountered an odd production issue with the java memcached
> client.  This is occuring in a memcached cluster of 30 nodes running
> server version 1.2.1, with java client version 1.5.1.  I realize
> neither of these are the latest and greatest versions of the
> respective software, but I see nothing as of yet in the change logs
> to indicate that our problem would be solved by upgrading.
> The issue is that when one or more server nodes go down and then
> later come back up, dead connections seem to persist in the client
> connection pools for an indefinite period.  We are aware of this
> because we can see the memcached client SockIOPool class logging the
> following error on some percentage of incoming requests (where "foo"
> is just the output of the socket's toString method and "bar" is the
> host).
> ++++ socket in avail pool is not connected: foo for host: bar
> The errors seem to (very very) slowly decrease over time, but a lot
> of them persist after 24 hours and the only remedy is to restart the
> application JVMs running the memcached client.  Note that while this
> error is occuring, the memcached node that died and then restarted
> seems to be getting a relatively normal volume of traffic.
> These are the settings we currently use on SockIOPool:
> pool.setMinConn(5);
> pool.setMaxConn(50);
> pool.setInitConn(5);
> pool.setSocketTO(1000);
> pool.setSocketConnectTO(100);
> pool.setFailover(false);
> pool.setFailback(true);
> pool.setAliveCheck(false);
> Any help would be greatly appreciated.
> Eli Bingham
> Senior Engineer
> Pandora Media, Inc.

Greg Whalin
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